The use of a Thermospray (TSP) in flame atomic absorption (FAA) increases sensitivity. Experimental data showed that a 75 mu m orifice and 0.05 cm 1D capillary produced a sensitivity increase of about 10(4) compared to commercial flame atomizer. The signal was independent of power input over a considerable power range.Based on this data a TSP nebulizer was built and used for interfacing HPLC and FAA. The instrument was used for cadmium speciation studies on urine. The presence of numerous cadmium compounds was revealed.With further modification on TSP construction design, even higher analytical sensitivity for ultra trace metal analysis and better compatibility for interfacing HPLC with MS, ICP-MS, FAAS, and ICP-AES can be expected.
Previous cadmium speciation studies using a modified thermospray (TSP)-coupled-HPLC-Flame AAS system gave significant improvements in limits of detection (LOD). Experimental data also revealed that a smaller capillary tip orifice size and a larger capillary internal diameter (ID) provided better LOD and relative standard deviation (RSD). Further studies to understand the desolvation mechanism inside the TSP capillary generated a new concept of the possible desolvation process occurring inside the heated TSP capillary. The separated components in the HPLC efficient were preconcentrated in a series of concentrated solute plugs producing concentrated plugs of free atoms and hence increased absorption.
Early work on cadmium speciation of body fluids using GC-AA indicated the presence of CdCl2, but other non-volatile Cd compounds were not detected (1). Such compounds may be detected by LC-AA.To this end, an HPLC-Flame AA system (FAAS) has been developed using a thermospray. This device greatly increased the sensitivity of the flame CFA system. Its use revealed the presence of numerous non-volatile cadmium compounds in urine and perspiration and confirmed our earlier observation that perspiration is a major process for removing cadmium from the body. Using data obtained, the half life of cadmium in the body is about 18 months rather than 20-30 years as currently believed.
